Air conditioning device

ABSTRACT

The invention relates to an air condition device consisting of recovery cells (1, 2), inlet (3) and exhaust ducts (4) leading to and from a room, and inlet (5) and exhaust ducts (6) located at the other end of the device and leading to and from the outdoor air, the air flown in the air conditioning device being controlled by means of rotating deflectors (7, 8). The deflectors (7, 8) consist of baffles fixed to different control axes (9, 10) and rotating about their axes, the air openings (11, 12) provided in the deflectors being located alternatingly at the same recovery cell (1, 2), where the air flow directions are reversed periodically.

[0001] This invention relates to an air conditioning device comprisingrecovery cells, inlet and exhaust ducts leading to and from a room, andinlet and exhaust ducts leading to and from the outdoor air and locatedat the other end of the device, the air flows in the air conditioningdevice being controlled by means of deflectors rotating about separateaxes.

[0002] In conjunction with air conditioning, the following issues mustbe considered: recovery of exhaust air energy, moisture balancing andcooling/heating. In addition, these matters have a different impact interms of geography. In cold zones, heat recovery is vital, in thetemperature zone cooling and moisture balancing are also primary issues,whereas the focus is on cooling and dehumidification of outdoor air inthe hot zone.

[0003] It has been stated that cooling entails costs that are about sixtimes those of heating. The cooling of outdoor air into indoor airrequires much energy in the warm zone. Due to the high connection powerrequired by cooling device compressors, operating such devices with theuse on renewable forms of energy is not justified.

[0004] In the summer, the relative humidity of indoor premises tends tobe too high, whereas it is too low in the heating season. This is due tothe fact that hot air may contain more humidity. For the moisturebalance to be ideal, expensive air dryers and humidifiers are needed.

[0005] Condensed humidity releases heat, and similarly, evaporatedhumidity binds heat. By making skilful benefit of these naturalphenomena, the relative humidity of indoor air can be kept in balanceand energy consumption reduced.

[0006] Air dehumidification is more difficult and expensive than merecooling. As a solution to this, it has even been proposed to recirculateindoor air that has been dried once, however, this involves the problemof lack of fresh air. Humans, animals and buildings themselves are inneed of fresh air. The reason for such solutions is the high energyconsumption caused by conventional techniques.

[0007] Besides humidity problems, moisture condensation in heat recoverycells results in the cell array freezing at temperatures below zerowithout additional heating of the cells. In conventional plate heatexchangers on bakeries, humidity associated with flour and yeast dustwill form a “dough” in the cells, so that air cannot pass through these.Then the heat from the ovens cannot be recovered, for instance.

[0008] Heated air may contain more humidity than cold air. Heated andmoist air that has been conducted to a duct system may result in mildewdamages, because mildew growth requires nothing but moisture and heat.

[0009] Impurities in indoor air cause serious sanitary and economicdamage, let alone problems related to comfort. Humans, animals andplants all suffer from these problems. Outdoor air may be purer thanindoor air, however, in cities and specifically in industrialenvironments the outdoor air is more polluted than the indoor air.

[0010] In the filters are not replaced according to instructions, theimpurities will increase. If the location of a filter is sufficientlyhot and humid, there will be bacterial growth on its surface, even oflethal legionella in the extreme.

[0011] Air contains particles different in size/diameter from those thatcan be seen with the bare eye—a diameter above 5 micrometers, visibleonly with a special microscope—a diameter less than 0.1 micrometer. Thegreatest impurities consist of e.g. hair, pollen and coal dust. Smallerimpurities are e.g. bacteria, dust which is hazardous for the lungs,sulphur compound fog, oil mist and lead monoxide. The smallest particlesconsist of viruses and fumes.

[0012] Air filters can be roughly divided into coarse filters, whichclean impurities that can be seen with the bare eye, fine and electricfilters, which clean also impurities visible only with a microscope, andfinally hepa filters, which clean practically all impurities.

[0013] Various solutions have been developed for all these knownpurposes, and they are method known per se. This invention allows theproblems mentioned above to be solved with one single device. Theinvention enables values to be combined and maximized, which are afunction of the following: 1. The accumulated mass. 2. The areatransferring heat, cold and humidity. 3. The air flow rate and the timerequires to achieve the condensation point.

[0014] Everyone skilled in the art knows the effect of these variables.Vital aspects of this invention are also its straightforward solution,low production costs and the low energy consumption required by thedevice. The air conditioning device of the invention is characterised bythe fact that both the deflectors consist of rotating baffles providedwith air inlets known per se and either separately or togethercontrolled. During the periodical rotation of the deflectors, thedirection of the air flows is reversed. The air flows to and from theair conditioning device have been provided by means of fans known perse, with the air openings in the deflectors mutually aligned.

[0015] In the winter, the operation of a heat recovery cell operating inthe regenerative counter flow principle is the following: as hot andcold indoor air passes through the cell, the impurities are directed outfrom the cell as the heat is transferred from the air into the cell, andthen the humidity is condensed, forming a mist film in the cell surface.

[0016] FI patent specification 100,133 discloses recovery cells anddeflectors similar to those of the invention, however, with thedifference that the air ducts directed to the indoor and outdoor air arealways located on the same side of the recovery cells (the device has ahot and a cold end) and that the air openings are always located at thesame cell, whereas in accordance with the patent, ducts leading both tothe outdoor and to the indoor air are located at the same end and theair openings are always located at different cells. In accordance withthe patent, a deflector controls air flows flowing in the samedirection, whereas in the invention, the provision described abovereverses the air flow directions using the counterflow principle. Theinvention yields the following advantages, among other things (i.a. onthe basis of the following tests: VTT/Oct. 4, 1995; RTE 10406/95 andSINTEF/Nov. 8, 1892/STF15F 82029, May 28, 1982/150164): 1) very hightemperature efficiency (VTT: 87.8%, SINTEF: 98%. 2) In hot (above 30°C.) and humid (relative humidity above 80%) outdoor conditions thedevice cools indoor air even by 3-5° C. without supplementary energy. 3)Properly used, the cell array will not freeze. 4) Low connection power.5) Balancing of the relative humidity of indoor air by 38-67%. Thedevice described in FI patent specification 100,133 does not providesuch functions nor such high efficiency, because it operates on theforward current principle.

[0017] The effect of the device of the invention on temperatures andhumidity are presented below. In the summer, with an indoor temperatureof 23° C., the air contains 7 g/m³ of water, implying 41% relativehumidity.

[0018] When a cell having a temperature of 23° C. is heating to 30° C.,water is discharged along with the air flow at a maximum rate of 6 g/m³.If the cell cools to 23° C., water will enter (26 g-17 g) in an amountof 9 g, because when saturated, air having a temperature of 23° C.contains 17 g of water.

[0019] When the outdoor air is warm and humid, the relative humidity ofindoor air also tends to rise because of losses. In this case as well,the invention will maintain the relative humidity of indoor air at about45%.

[0020] In the winter, the invention has the following function: air at−10° C. contains 2 g/m³ of water. Indoor air is heated to 20° C.,binding 14 g of humidity. The amount of discharged water (air at 20° C.)is 7 g/m³. When the air is cooled to −10° C., it can remove only 2 g ofwater. The difference (7−2) 5 g+2 g. and thus the device can bring back7 g of water inside. However, due to losses (10%) the relative indoorhumidity drops to about 30% in reality in the winter.

[0021] Should the conventional indoor air cooling if the invention beinadequate, separate evaporating cooling can be used as follows. Bysaturating exhaust air ( +20 ° C.=16 g/m³ of water) an effective coolingdevice is obtained. The outdoor air +30° C. (25 g/m³ of water). When tooutdoor air leaves the room through the cell, its humidity rises from 16g to 25 g=a difference of 9 g/m³, i.e. about 30% of 25 g. As itevaporates into the outdoor air, water cools the cells (binding heat) atthe same rate (25−16=9, i.e. about 30%), in other words, the evaporationof humidity from the cell cools the cell and the air (30% of 20°C.)=about 6° C. Theoretically, with a 10% loss, thus about 5° C.; whichcorresponds also to the 3-5° C. of the tests conducted in the practice(SINTEF/Jul. 2, 1982).

[0022] The work Aittomdki, A., Karkiainen.S., Vehmaan-Kreula.K,Uimahallien ilmankuivausjarjestelmien vertailu, (Comparison of airdrying systems in public swimming baths), Tampereen TKK (TampereUniversity of Technology), Energy and Process Engineering, UDK694.97,725.74, Report 131, Tampere 1997, ISBN 951-722-938-0, ISSN1238-4747, states the following on page 36:

[0023] The following conclusions can be drawn from the results:

[0024] the larger the heat recovery area, the less heat pump decreasesheat consumption

[0025] an increase in the heat recovery area reduces heat consumptionmore than an increase in the evaporator area.

[0026] the target humidity of the bath hall has a strong impact on theheat consumption. By contrast, limiting temperature (−10° C. or 0° C.)of the amount of outdoor air has no notable impact.

[0027] a heat pump may cut the energy costs, however, the difference istoo small for investment amortisation.

[0028] The apparatus of the invention comprises regenerative heatrecovery combined with drying function on the absorption principle (areaincrease). As described above, the invention may be further connectedwith a heat pump system, and then any remaining humidity will be removedfrom the evaporator. One single apparatus may hence include all the mainfunctions required for air drying.

[0029] The cells of the apparatus of the invention are alternatingly hotand cool, so that the air humidity is alternatingly condensed andevaporated in the set of cells. Owing to this vital property, the deviceoperates faultlessly also in bakeries.

[0030] The access of pollen and any other impurities can be prevented bymounting a filter at the outdoor air end of the recovery cell, so thatimpurities adhere to the filter and return to the inlet side when theair flow direction is reversed, without contaminating the indoor air orthe heat recovery cell. A major advantage of the invention is that theair filter does not require cleaning, and thus its cleaning efficiencywill remain the same as that of a new device, and no bacterial growthwill occur. By varying the type of filter the cleaning efficiency isvaried. In hospitals for instance, hepa filters can be used, whereaslower filtering capacity is enough for other purposes of use. The filtershould be selected such that impurities in indoor air pass through,whereas impurities in outdoor air are caught in it.

[0031] In a regenerative heat recovery device controlled with baffles,the cells might freeze. This is due to the fact that the bafflesgenerate underpressure and overpressure, so that the humidity containedin the air might be condensed to water on the cell surfaces. Theadditional heating then required results in poorer energy management andhigher production costs, and thus in a longer period of earning theprice of the device.

[0032] In accordance with the invention, the deflectors can becontrolled by means of different shafts. In one embodiment of theinvention, the deflector on the exhaust air side of cell array can becontrolled to turn with a delay, further minimizing mixing of the airflows in the cell. On advantage of the invention over large units isthat the long shaft of such units tends to be twisted, and then theturning of the deflectors in beyond control. On the other hand, theinvention makes possible also that the deflectors are controlled torotate by the same axis, accordingly FI patent 100,133.

[0033] In the warn zone, the heat recovery cell excludes the heat.Should the air deriving from the air recovery cell still be too hot, itcan be directed from the cooling unit condenser further to anevaporator, from where it is conducted as cooled air to the indoorpremises. A conventional cooling system cools outdoor air (from e.g. 40°C.) to indoor air (20 ° C.) by means of a compressor. The amount ofenergy required is about 1.5 kW. Since, in accordance with theinvention, 90% of the difference between outdoor and indoor temperaturesis kept outside, the compressor needs to cool only 10% (2° C. in theexample). The required connection power is only 200 W. The coolingsystem comprises a compressor, a heat transfer medium including pipingand other appliances, and a condenser and an evaporator, which are knownper se.

[0034] The invention can also be used in connection with conventionalcooling and air conditioning and heat recovery systems by directing theinlet ducts leading to the outdoor air first to the device of theinvention, ant then the air is directed to a cooling or air conditioningunit. With this arrangement, conventional devices will yield thebenefits of the invention.

[0035] In conventional air conditioning, the periods for heat recoverydevices and cooling devices to earn their price get very long. Besidesthe price, there is the question of additional energy required formelting regarding the heat recovery devices. On the one hand, coolingdevices operating with an outdoor air heat pump are unable to functionat temperatures below zero. On the other hand, exhaust air heat pumpsare of no use when the outdoor temperature in higher than the indoor airtemperature. Thus, such devices will have a very short service periodper year. Should both the systems be needed, the price would be evenhigher. Calculated under the (winter) conditions in Finland and with theaverage electricity prices in Finland, the period over which the deviceof the invention will earns its price is about three years. Calculatedin combination with a cooling device and under the hot (summer)conditions in the USA and with the average electricity prices in theUSA, the device may have earned its price within less than a year. Theextremely good Seasonal Performance Factor (SPF) results from the longutilization time per year, which is actually the whole year, because thedevice can act as a heat pump both in the winter and in the summer.

[0036] Utility Model No 4123 describes in general terms a regenerativecounter-current air conditioning device, without explaining in detailthe manner of reversing the air flow directions.

[0037] Various embodiments of the invention are described in thedependent claims.

[0038] The invention in described below by means of an example and withreference to the accompanying which is a schematic view of the airconditioning device and air flows provided in the air conditioningdevice.

[0039] The air conditioning device consist of recovery cells 1, 2, inlet3 and exhaust ducts 4 leading to and from a room, and inlet 5 andexhaust ducts 6 leading to and from the outdoor air. The air flows arecontrolled by means of rotating deflectors 7, 8. The deflectors 7, 8consist of baffles fixed to either different control axes 9, 10 or samecontrol axis 9, 10 and rotating about their axis and provided with airopenings 11, 12. The deflectors 7, 8 are located on axes/axis 9, 10 oneither side of the recovery cells 1, 2. The deflectors 7, 8 have an evennumber of air openings 11, 12, through which the air flows are directedalternatingly to the recovery cells 1, 2, where the air flow directionsare inverse and are periodically reversed. The air flows are indicatedby means of arrows. The air openings 11, 12 in the deflectors 7, 8 forman approx. 90 angle. The top and bottom pressure balancing chambers 13,14 have stationary partitions 15, 16. The deflector can be rotatedperiodically by means of a timer in the same direction orreciprocatingly, or even continuously by adjusting the rotating speedwith the aid of a motor (not shown in the drawning). The recovery cells1, 2 are long in the air flow direction, having a length 2-5 times theirwidth. The recovery cells can be replaced according to the climate andthe service conditions of the device, for instance by increasing theheat recovery or the evaporating function, i.e. the cooling,respectively. The bulk, area, turbulence of the cells 1, 2 and the airflow rate vary under these varying conditions. The heat recoveryefficiency and the humidity balancing can be adjusted with a timer sothat the alternating periods or rotation speeds of the deflectors can bealtered. At the outdoor end of the ducts 5, 6 of the recovery cells 1, 2an air filter 17 has been mounted, which prevents the access ofimpurities from the outdoor air, yet during the subsequent period letsthrough smaller impurities from the indoor air, the air flow entrainingalso outdoor impurities which have adhered to the filter.

1. An air conditioning device consisting of recovery cells (1, 2), inlet(3) and exhaust ducts (4) leading to and from a room, and inlet (5) andexhaust ducts (6) located at the other end of the device and leading toand from the outdoor air, the air flows in the air conditioning devicebeing controlled by means of rotating deflectors (7, 8), characterisedin that the deflectors (7, 8) consist of baffles rotating about theiraxes (9, 10), in which air openings (11, 12) known per se are locatedalternatingly at the same recovery cell (1, 2).
 2. An air conditioningdevice as defined in claim 1, characterised in that the deflectors (7,8) have an even number of air openings (11, 12), through which the airflows are directed alternatingly to the recovery cells (1, 2), where theair flow directions are reversed periodically.
 3. An air conditioningdevice as defined in claim 1, characterised in that the deflectors (7, 8) are circular baffles having air openings (11, 12 ) in the shape of asector.